An under-strength Arsenal side were well beaten by Chelsea as they went down 3-0 in their pre-season friendly at the Bird's Nest in Beijing.

Willian opened the scoring before a Michy Batshuayi double either side of half-time accentuated the difference between the two teams.

Here, are three talking points from the game:

Is slow start a worry?

Arsenal were dramatically beaten 4-3 by Liverpool at the Emirates Stadium on the opening weekend of last season and that proved significant in May. Ultimately, the Reds found themselves only one point ahead of the Gunners in the race for fourth, bringing Arsene Wenger's run of 20 consecutive top-four finishes to an end.

So Arsenal will be looking to begin the forthcoming campaign rather more convincingly. On this evidence, there is much work to do. The penalty shootout victory over Bayern Munich in midweek masked the fact that Wenger's men looked vulnerable for much of the match and that frailty was exposed again by Chelsea in Beijing.

Given that this was only Chelsea's second pre-season friendly, and their first in front of a crowd, that is a little surprising.

This was Arsenal's fourth game but they still looked off the pace against the champions. Wenger will hope that can be attributed to a sickness bug that has afflicted the squad. How damaging it proves to be may not be known until next month.

Problems with back three?

The big issue for Wenger seems to be the shape. Having had some success with a switch to a back-three towards the end of last season, the Arsenal boss appears willing to stick with the formation for 2017/18. But the early signs are that the players are having some problems in making it work - they could even have conceded inside 20 seconds against Chelsea.

Ainsley Maitland-Niles was filling in at right centre-back and was a little sloppy in his work, while Nacho Monreal was at fault in showing Willian onto his right foot for the opening goal. With Per Mertesacker failing to get close enough to Batshuayi for his first too, it was not an encouraging showing from Arsenal's makeshift defence.

Of course, the personnel will change for the Community Shield, but if the plan was to use pre-season to hone the system then Arsenal have a way to go. As well as Maitland-Niles and Monreal, Wenger has also used Mohamed Elneny in the three. If this system was the plan, could the Arsenal boss regret not signing some specialists for the roles?

Could Sanchez be the key?

One man ideally suited to a 3-4-3 formation is Alexis Sanchez but he is not involved in this tour as he recovers from his exertions at the Confederations Cup with Chile. Wenger is still outwardly insistent that Arsenal's star player will remain at the club for the final year of his contract and it is already tempting to imagine how he might link up with Alexandre Lacazette.

The new signings link up with Mesut Ozil showed some promise against Bayern and the German playmaker showed some glimpses of his quality against Chelsea too. The prospect of Lacazette's movement in the final third is an intriguing one - particularly if it can free up space for Sanchez to exploit. But can Arsenal really risk keeping an unhappy player?

If Sanchez does leave, with Paris Saint-Germain reportedly joining Manchester City in the hunt for his signature, it is clear that Arsenal need to add a replacement. After finishing fifth in the Premier League, the onus is on Wenger to work to close the gap on those teams above. Fail to address it and more results like Saturday's defeat in Beijing could be on their way.